1 .. highlightlang:: none 2 3 .. _installing-index: 4 5 ***************************** 6 Installing Python Modules 7 ***************************** 8 9 :Email: distutils-sig (a] python.org 10 11 As a popular open source development project, Python has an active 12 supporting community of contributors and users that also make their software 13 available for other Python developers to use under open source license terms. 14 15 This allows Python users to share and collaborate effectively, benefiting 16 from the solutions others have already created to common (and sometimes 17 even rare!) problems, as well as potentially contributing their own 18 solutions to the common pool. 19 20 This guide covers the installation part of the process. For a guide to 21 creating and sharing your own Python projects, refer to the 22 :ref:`distribution guide <distributing-index>`. 23 24 .. note:: 25 26 For corporate and other institutional users, be aware that many 27 organisations have their own policies around using and contributing to 28 open source software. Please take such policies into account when making 29 use of the distribution and installation tools provided with Python. 30 31 32 Key terms 33 ========= 34 35 * ``pip`` is the preferred installer program. Starting with Python 2.7.9, it 36 is included by default with the Python binary installers. 37 * a virtual environment is a semi-isolated Python environment that allows 38 packages to be installed for use by a particular application, rather than 39 being installed system wide 40 * ``virtualenv`` is a third party tools for creating virtual environments, it 41 is defaults to installing ``pip`` into all created virtual environments. 42 * the `Python Packaging Index <https://pypi.org>`__ is a public repository of 43 open source licensed packages made available for use by other Python users 44 * the `Python Packaging Authority 45 <https://www.pypa.io/en/latest/>`__ are the group of 46 developers and documentation authors responsible for the maintenance and 47 evolution of the standard packaging tools and the associated metadata and 48 file format standards. They maintain a variety of tools, documentation 49 and issue trackers on both `GitHub <https://github.com/pypa>`__ and 50 `BitBucket <https://bitbucket.org/pypa/>`__. 51 * ``distutils`` is the original build and distribution system first added to 52 the Python standard library in 1998. While direct use of ``distutils`` is 53 being phased out, it still laid the foundation for the current packaging 54 and distribution infrastructure, and it not only remains part of the 55 standard library, but its name lives on in other ways (such as the name 56 of the mailing list used to coordinate Python packaging standards 57 development). 58 59 60 Basic usage 61 =========== 62 63 The standard packaging tools are all designed to be used from the command 64 line. 65 66 The following command will install the latest version of a module and its 67 dependencies from the Python Packaging Index:: 68 69 python -m pip install SomePackage 70 71 .. note:: 72 73 For POSIX users (including Mac OS X and Linux users), the examples in 74 this guide assume the use of a :term:`virtual environment`. You may install 75 ``virtualenv`` to provide such environments using either pip 76 (``pip install virtualenv``) or through your system package manager 77 (commonly called ``virtualenv`` or ``python-virtualenv``). 78 79 For Windows users, the examples in this guide assume that the option to 80 adjust the system PATH environment variable was selected when installing 81 Python. 82 83 It's also possible to specify an exact or minimum version directly on the 84 command line. When using comparator operators such as ``>``, ``<`` or some other 85 special character which get interpreted by shell, the package name and the 86 version should be enclosed within double quotes:: 87 88 python -m pip install SomePackage==1.0.4 # specific version 89 python -m pip install "SomePackage>=1.0.4" # minimum version 90 91 Normally, if a suitable module is already installed, attempting to install 92 it again will have no effect. Upgrading existing modules must be requested 93 explicitly:: 94 95 python -m pip install --upgrade SomePackage 96 97 More information and resources regarding ``pip`` and its capabilities can be 98 found in the `Python Packaging User Guide <https://packaging.python.org>`__. 99 100 .. seealso:: 101 102 `Python Packaging User Guide: Installing Python Distribution Packages 103 <https://packaging.python.org/en/latest/installing/>`__ 104 105 106 How do I ...? 107 ============= 108 109 These are quick answers or links for some common tasks. 110 111 ... install ``pip`` in versions of Python prior to Python 2.7.9? 112 ---------------------------------------------------------------- 113 114 Python only started bundling ``pip`` with Python 2.7.9. For earlier versions, 115 ``pip`` needs to be "bootstrapped" as described in the Python Packaging 116 User Guide. 117 118 .. seealso:: 119 120 `Python Packaging User Guide: Requirements for Installing Packages 121 <https://packaging.python.org/en/latest/installing/#requirements-for-installing-packages>`__ 122 123 124 .. installing-per-user-installation: 125 126 ... install packages just for the current user? 127 ----------------------------------------------- 128 129 Passing the ``--user`` option to ``python -m pip install`` will install a 130 package just for the current user, rather than for all users of the system. 131 132 133 ... install scientific Python packages? 134 --------------------------------------- 135 136 A number of scientific Python packages have complex binary dependencies, and 137 aren't currently easy to install using ``pip`` directly. At this point in 138 time, it will often be easier for users to install these packages by 139 `other means 140 <https://packaging.python.org/en/latest/science/>`__ 141 rather than attempting to install them with ``pip``. 142 143 .. seealso:: 144 145 `Python Packaging User Guide: Installing Scientific Packages 146 <https://packaging.python.org/en/latest/science/>`__ 147 148 149 ... work with multiple versions of Python installed in parallel? 150 ---------------------------------------------------------------- 151 152 On Linux, Mac OS X and other POSIX systems, use the versioned Python commands 153 in combination with the ``-m`` switch to run the appropriate copy of 154 ``pip``:: 155 156 python2 -m pip install SomePackage # default Python 2 157 python2.7 -m pip install SomePackage # specifically Python 2.7 158 python3 -m pip install SomePackage # default Python 3 159 python3.4 -m pip install SomePackage # specifically Python 3.4 160 161 (appropriately versioned ``pip`` commands may also be available) 162 163 On Windows, use the ``py`` Python launcher in combination with the ``-m`` 164 switch:: 165 166 py -2 -m pip install SomePackage # default Python 2 167 py -2.7 -m pip install SomePackage # specifically Python 2.7 168 py -3 -m pip install SomePackage # default Python 3 169 py -3.4 -m pip install SomePackage # specifically Python 3.4 170 171 .. other questions: 172 173 Once the Development & Deployment part of PPUG is fleshed out, some of 174 those sections should be linked from new questions here (most notably, 175 we should have a question about avoiding depending on PyPI that links to 176 https://packaging.python.org/en/latest/mirrors/) 177 178 179 Common installation issues 180 ========================== 181 182 Installing into the system Python on Linux 183 ------------------------------------------ 184 185 On Linux systems, a Python installation will typically be included as part 186 of the distribution. Installing into this Python installation requires 187 root access to the system, and may interfere with the operation of the 188 system package manager and other components of the system if a component 189 is unexpectedly upgraded using ``pip``. 190 191 On such systems, it is often better to use a virtual environment or a 192 per-user installation when installing packages with ``pip``. 193 194 195 Pip not installed 196 ----------------- 197 198 It is possible that ``pip`` does not get installed by default. One potential fix is:: 199 200 python -m ensurepip --default-pip 201 202 There are also additional resources for `installing pip. 203 <https://packaging.python.org/tutorials/installing-packages/#install-pip-setuptools-and-wheel>`__ 204 205 206 Installing binary extensions 207 ---------------------------- 208 209 Python has typically relied heavily on source based distribution, with end 210 users being expected to compile extension modules from source as part of 211 the installation process. 212 213 With the introduction of support for the binary ``wheel`` format, and the 214 ability to publish wheels for at least Windows and Mac OS X through the 215 Python Packaging Index, this problem is expected to diminish over time, 216 as users are more regularly able to install pre-built extensions rather 217 than needing to build them themselves. 218 219 Some of the solutions for installing `scientific software 220 <https://packaging.python.org/en/latest/science/>`__ 221 that is not yet available as pre-built ``wheel`` files may also help with 222 obtaining other binary extensions without needing to build them locally. 223 224 .. seealso:: 225 226 `Python Packaging User Guide: Binary Extensions 227 <https://packaging.python.org/en/latest/extensions/>`__ 228
